Storage medium

 
 
Hard drives are one of the more common forms of computer storage.
(show full size)

The terms "storage" or "memory" refer to the parts of a computer that retain data for some period of time, possibly even after the computer is turned off.

Different types and different purposes

There are many ways in which types of storage can be categorised. These include

• primary or secondary.
• volatile or non-volatile.
• read-only memory, WORM, or read-write.
• media categories, e.g., semiconductor, optical, magneto-optical, and magnetic.

Normally, "memory" refers to primary, semiconductor-based storage, but this is a very blurred distinction.

Each type of storage is suited for different purposes, and most computers contain several types: primary, secondary, and volatile.

Primary storage

Primary storage contains data that are actively being used (for example, the programs currently being run and the data they are operating on). It is typically high-speed, relatively small, is often (but not always) volatile. It is sometimes referred to as "Main Memory."

Secondary storage

Secondary storage, also known as peripheral storage, is where the computer stores information that is not necessarily in current use. It is typically slower and higher-capacity than primary storage. It is almost always non-volatile.

Volatile storage

Volatile storage loses its contents when it loses power; non-volatile storage does not.

A list of storage devices

• CD-R
• CD-ROM
• CD-RW
• Cache memory
• Core memory or core storage
• Delay line memory
• DVD-RAM
• DVD-ROM
• Flash memory
• Floppy disk
• Hard disk
• Holographic memory
• Magnetic bubble memory
• Magnetic tape
• Magnetic drum
• Magneto Optical
• Memory stick
• Mylar tape
• NVRAM
• Punch card
• Paper tape
• RAM
• ROM
• Selectron tube
• Smartdisk
• Thin film magnetic memory
• VRAM
• Williams tube
• WRAM

A list of memory-related software

• Aard
• QEMM

See also

• Memory allocation
• Write protection
• Computer file
• List of file formats
• Wait state